In general, an optical reading apparatus comprises:                a light emitting section, comprising at least one light source—for example one or more LEDs or a laser light source—, optional optical shaping and/or focusing components for the light emitted by the light source, and optional means for scanning the light emitted by the light source, for example one or more rotating or oscillating mirror surfaces, and        a light receiving section comprising at least one photosensitive element, for example one or more photodiodes or a CCD or C-MOS device, generating an electrical signal having an amplitude proportional to the light incident on it, and optional optical components for collecting and/or focusing the light onto the photosensitive element.        
The optional shaping and/or focusing components of the emitting section and the optical collecting and/or focusing components of the receiving section can partly or totally coincide. The casing of an optical reading apparatus thus comprises an emitting window, a receiving window, or an emitting/receiving window.
An optical reading apparatus generally comprises also devices for processing the output signal of the photosensitive element or elements of the receiving section, such as an amplifier, an analogue-to-digital converter, or a sampler.
In the particular case of bar code or two-dimensional two-color—commonly black and white—code readers, moreover, a digitizer can be comprised, in addition to or as an alternative to the analogue-to-digital converter or to the sampler.
Moreover, an optical reading apparatus can comprise a microprocessor processing unit. In the case of an optical code reader such a processing unit, commonly indicated as a “decoder”, is intended to decode the optical code being read, including the optional reconstruction of the optical code from partial scan lines. In the case of other optical reading apparatuses, such a processing unit is intended to perform the specific function of the optical reading apparatus, for example to determine measures of distances and volume of objects, to detect their presence, etcetera.
The expression “automatic” is used as opposed to the “portable” or “manual” terms, that is to say, to indicate an optical reading apparatus to be used without human actuation. Such apparatuses, also known as “unattended scanners”, are used, for example, at a conveyor belt (or other handling means) on which items to be detected travel, or at a fixed station where an operator manually enters the items to be detected, or also on machinery moving the optical reader, such as for example on a forklift in a store. Item detection can comprise the reading of an optical code and/or the measurement of a distance and/or of a volume, etcetera.
An automatic optical reading apparatus generally is part of a complex system, wherein it interacts with other optical reading apparatuses, other electro-optical devices such as height sensors, other electrical, electro-mechanical and/or electronic devices, in particular for data processing.
More in particular, the output signal of the photosensitive element of the receiving section, optionally treated and/or processed by the above-mentioned additional components, can be transmitted outside the optical reading apparatus to an external processing unit for further processing. Moreover, the information content detected by the optical reader (the particular code read, the determined distance or volume, an ON/OFF signal, etcetera) is typically transmitted outwards, for example in a control unit of an automatic item sorting system, in the management of a store, in an automatic machinery, a cash register, etcetera.
Moreover, besides the necessary power supply, an optical reading apparatus typically receives one or more input control signals. For example, in a system for detecting items travelling on a conveyor belt, besides one or more optical code readers oriented so as to read an optical code wherever arranged on the surface of an item and an optional device for measuring volumes, auxiliary devices may be present, such as a sensor for detecting the presence of an item on the conveyor belt, suitable for emitting a signal to actuate the optical reading apparatuses and the other components; a device for measuring the speed of the conveyor belt as a parameter to be taken into account in the processing of the photosensitive element output signal; devices for measuring the height and/or position of the item on the conveyor belt, intended to provide useful indications for focusing the optical code and, more in general, for performing a good reading.
The connection of each optical reading apparatus to the power supply and/or to the other devices of the system where it is used, such as the above auxiliary devices and/or the external processing unit, is typically realized via cable and preferably through removable connectors, because of the complexity of the connections themselves, which often makes the use of a single cable impossible, and because many connections are standardized.
As an alternative or in addition thereto, in some applications there can be provided a cordless interface through radio units and antennae or infrared transceivers.
An automatic optical reading apparatus therefore generally comprises an outside interface section.
In an optical reading apparatus, the emitting section and the receiving section, which comprise fragile components, are especially subject to wear and failures. In case of failure or breakage of a component of a known optical reading apparatus, the entire apparatus must be replaced at least at the end user's level.
In fact, the integrity of the casing of known optical reading apparatuses, housing all the emitting, receiving and interface sections, as well as the above optional additional components, cannot be tampered by the end user due to the safety regulations, in particular in the case of laser light sources.
The replacement of the entire optical reading apparatus requires an in-depth knowledge of the entire system, since the substitute optical reading apparatus and the components interacting with it must at least be connected again, resulting in a time-consuming and costly operation.
Known optical reading apparatuses are not only produced in a wide range of functional performances, but also in a range of layouts.
In particular, the exit of connection cables or connectors from the casing of common optical reading apparatuses may be on a wall of the casing of the optical reading apparatus,—generally known as “interface wall”—, opposed to or adjoining a wall of the casing containing the light emitting/receiving window. The antennae and transceivers provided for cordless communication have a similar distribution on the casing of the optical reading apparatus.
The installation of a particular known automatic optical reading apparatus is sometimes difficult due to the restricted space available, which does not allow installing the apparatus with its wall containing the emitting/receiving window facing the intended reading field due to the space taken up by the connection cables at a predetermined wall of the apparatus casing. This applies to a greater extent in case of interface through connectors, that can take up a space even equal to 30-40% of the overall size of the optical reading apparatus.
Also in case of cordless communication, given the directionality of typically used antennae and the need for conjugated transceivers to face each other, the predetermined mutual orientation of the wall containing the emitting/receiving window and of the interface wall does not always coincide with the optimum arrangement of the optical reading apparatus in the complex system where it is used.
In these cases, it is necessary to use a different optical reading apparatus, wherein the interface wall is arranged in a different manner with respect to the wall containing the emitting/receiving window, or to use light returning or deflecting mirrors. The first solution implies the need of producing—and thus assembling and stocking—optical reading apparatuses having identical or equivalent performance, differing in the outside casing only.
The second solution implies even more considerable disadvantages. In fact, the installation of the optical reading apparatus together with the necessary deflecting mirrors implies complex alignment procedures.
In known optical reading apparatuses, the control of the analogue components of the emitting section and of the receiving section is performed by an electronic controller, which however is in turn controlled and programmed through algorithms residing in the single microprocessor processing unit present, that is to say, the decoder in the case of an optical code reader, or the processing unit intended to determine distances and volumes in the case of measuring devices.
In optical reading apparatuses the need may arise of configuring some parameters of the apparatus internal components on the spot. Such parameters comprise, among the others, the gain of signal amplifiers and preamplifiers, the band-pass of the various electric and electronic components, the switching thresholds applied in the digitalization of the output signal of the photosensitive element (or of such output signal after processing through the analogue-to-digital converter or the sampler), the scanning speed or speed profile of the light beam in the case of a laser reader, for example the speed profile of a motor for moving a scanning mirror or mirror system, as well as some parameters of the treatment and/or processing algorithms of the output signal of the photosensitive element.
As a general rule, the programming of such parameters, in particular of analogue component parameters, requires a fine tuning on the spot, and thus the presence of a high-level operator both during the first installation of the optical reading apparatus and during replacement thereof, in case of failure or breakage of a component.
The complex systems wherein the optical reading apparatuses are installed are often provided with a certain redundancy, in particular, with a redundant number of optical code readers with at least partly superimposed reading areas to ensure good reading performances in case of particularly damaged optical codes.